MARACOOS Provides Data for Annapolis, Maryland Flood Mitigation

Above: Local businesses are impacted by frequent flooding in Annapolis, MD. Image credit: City of Annapolis Office of Emergency Management

April 1st, 2019

The City of Annapolis, Maryland is notorious for its susceptibility to nuisance flooding, primarily between the months of March and September, due to its proximity to the coastline. Nuisance flooding is minor to moderate coastal flooding that causes localized impacts such as the inundation of streets and parking lots. Water from the Chesapeake Bay comes up through storm drains at high tide and intensifies when winds originate from the south or east. Visitors are sometimes surprised to see flooding even on beautiful days with no precipitation, which explains why nuisance flooding is also sometimes called “blue sky” flooding.

A 2014 NOAA study found that Annapolis has witnessed a 925% increase in annual nuisance flooding events since the 1960’s. This is the highest increase in the nation, and Annapolis now experiences an average of approximately 39.3 days of coastal flooding per year.

The first place in downtown Annapolis where nuisance flooding causes an impact is the parking lot at City Dock. The water begins to pool around the storm drain next to the Harbormaster’s Office and can sometimes envelop the entire parking lot. As a result, City Dock businesses lose revenue and customers must maintain vigilance to avoid damage to their vehicles. A February 2019 study by Stanford researchers and the U.S. Naval Academy found that businesses at City Dock suffer approximately $86,000-$172,000 annually in lost business due to nuisance flooding. Higher levels of nuisance flooding periodically close Compromise Street, which serves as a vital link between the Eastport peninsula and downtown Annapolis. Compromise Street is also an emergency evacuation route, which makes nuisance flooding in Annapolis a life safety concern.

The Annapolis Office of Emergency Management protects the safety of Annapolis residents, businesses, and visitors against public threats and disasters, including nuisance flooding events. Emergency Management coordinates flood response and supports daily, short-term, and long-term plans and flood protection initiatives. This comprehensive approach continues to reduce the impact of flooding on community infrastructure and preserve lives.

MARACOOS data are a crucial component of both daily flood response and long-term planning. The lack of precise flooding data would cause the City of Annapolis to either greater or lesser flooding than anticipated, which can exacerbate community impacts in one case or expend Annapolis flood preparation resources unnecessarily in the other. The Office of Emergency Management reviews MARACOOS data daily to assess the threat of nuisance flooding, and the data assist in keeping Annapolis safe and prepared in this ongoing and escalating challenge.

MARACOOS data also support a collaboration between the City of Annapolis and the U.S. Naval Academy to address long-term flood mitigation needs. This partnership produced data analysis of exponentially increasing coastal flooding, which Emergency Management used to convince the Federal Emergency Management Agency (FEMA) to support a pending $3M grant application that will contribute to a long-term flood mitigation initiative in downtown Annapolis. This project will install one water pumping station first at the north side of the Annapolis Harbor, then a second on the south side, in addition to backflow preventer devices on storm drains and improved water conveyance. By implementing mechanisms to mitigate nuisance flooding and diminish its impact on the Annapolis community, the City of Annapolis can better ensure the safety of its citizens against natural threats. With the help of MARACOOS, the City can continue long-term flood analyses to evaluate the effectiveness of their mitigation strategies and improve communication with other agencies, like FEMA, that invest in the City’s protection efforts.